1. Field of the Invention
The present invention relates to a vehicle seat including a seat pad, a seat cover covering the seat pad, an air bag inside the seat, and a jump-out portion (a fragile part from which the air bag jumps out of the seat), and a manufacturing method of a seat pad.
2. Description of Related Art
As this type of vehicle seat, there has been known a vehicle seat including a seat cushion, and a seatback rising from the seat cushion (see Japanese Patent Application Publication No. 2001-180422 (JP 2001-180422 A)). In this vehicle seat, the seatback includes a generally arch-shaped seat frame that forms a seat framework, a seat pad for elastically supporting an occupant, an air bag device, and a breaking slit (corresponding to a jump-out portion) provided in the seat pad. The seat pad is typically a member made of foam resin, forming a seat outer shape, and elastically supporting an occupant, and its front side is covered with a seat cover. Further, the air bag device is a housing including an air bag that expands due to inflow of air, and is attached to the seat frame so as to be placed on a seat side portion and a back side of the seat pad.
Further, the breaking slit is a long hole penetrating through the seat pad in its thickness direction, and is formed in that part of a thin side portion of the seat pad which covers the air bag device. In the technique as known in the art, a plurality of breaking slits is formed intermittently on a side face of the seat pad so as to have a generally transverse U shape in a side view. At this time, a bridge portion, which is a normal seat-pad portion, is placed between breaking slits adjacent to each other, so as to prevent as much as possible bending deformation of that side face of the seat pad which is thin and fragile. At the time of a vehicle collision, the air flows into the air bag in response to a signal caused due to the vehicle collision, so that the air bag expands and breaks through a seat-pad portion in which the breaking slits are formed. Further, the air bag that expands pushes aside the seat-pad portion around the breaking slits and jumps out of the seat by partially breaking the seat cover.